Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$191.65	4.498%	$200.2704	$200.27	$200.25	$200.30
Purchase #2	$35.78	3.228%	$36.935	$36.94	$36.95	$36.90
Purchase #3	$184.64	11.828%	$206.4792	$206.48	$206.50	$206.50
Purchase #4	$117.36	5.526%	$123.8453	$123.85	$123.85	$123.80
Purchase #5	$185.37	6.392%	$197.2189	$197.22	$197.20	$197.20
Purchase #6	$237.70	11.323%	$264.6148	$264.61	$264.60	$264.60
Purchase #7	$11.61	4.457%	$12.1275	$12.13	$12.15	$12.10
7 purchase totals =	$964.11		$1,041.4911	$1,041.50	$1,041.50	$1,041.40